linux-kernel - Re: [PATCH] KVM: arm64: Use different pointer authentication keys for pKVM

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Message-ID: <ZIiY8lrLKv4amCu7@google.com>
Date:   Tue, 13 Jun 2023 16:27:30 +0000
From:   Mostafa Saleh <smostafa@...gle.com>
To:     Oliver Upton <oliver.upton@...ux.dev>
Cc:     kvmarm@...ts.linux.dev, maz@...nel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        suzuki.poulose@....com, kaleshsingh@...gle.com, tabba@...gle.com,
        yuzenghui@...wei.com, catalin.marinas@....com, james.morse@....com,
        will@...nel.org
Subject: Re: [PATCH] KVM: arm64: Use different pointer authentication keys
 for pKVM

Hi Oliver,

On Tue, Jun 13, 2023 at 12:16:02PM +0000, Oliver Upton wrote:
> On Tue, 16 May 2023 14:15:31 +0000, Mostafa Saleh wrote:
> > When the kernel is compiled with CONFIG_ARM64_PTR_AUTH_KERNEL, it
> > uses Armv8.3-Pauth for return address protection for the kernel code
> > including nvhe code in EL2.
> > 
> > Same keys are used in both kernel(EL1) and nvhe code(EL2), this is
> > fine for nvhe but not when running in protected mode(pKVM) as the host
> > can't be trusted.
> > 
> > [...]
> 
> Applied to kvmarm/next, thanks!
> 
> [1/1] KVM: arm64: Use different pointer authentication keys for pKVM
>       https://git.kernel.org/kvmarm/kvmarm/c/fb737685beee
> 
> --

Thanks! I did more testing and I found a bug in this patch.

It seems there is another entry point for the kenrel where pauth was
not handled properly "kvm_host_psci_cpu_entry", I will investigate this
further and send V2.

Sorry for the inconvenience!

Thanks,
Mostafa